Robert Edsall, Mark Harrower, and Jeremy L. Mennis.
  <b>Tools for visualizing properties of spatial and temporal
  periodicity in geographic data</b>.
  <i>Computers & Geosciences</i>, pages 109-118, 2000.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Edsall-2000-STP.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Edsall-2000-STP.bib">(bibtex:
  Edsall-2000-STP)</A>.<br />